This invention relates to a combination moisture and hydrogen getter composition, and a method for scavenging moisture in a closed container during storage or service.
It is often desirable to prevent the possibility of moisture accumulation or condensation in closed containers during long periods of storage or service, especially sealed electronic and mechanical component containers. Most desiccants used for such purposes, e.g., molecular sieves, require a desiccant activation procedure, e.g., heating at 300.degree. F. for 48 hours at less than 10 torr, and the desiccant must therefore be activated apart from the apparatus. Furthermore, the apparatus itself requires expensive procedures to keep all parts dry after assembly of the activated desiccant. One procedure involves activating the desiccant, bonding the desiccant to the empty container, welding the container to the lid that carries the electronic assembly, potting the assembly with rigidizing foam and finally purging, back filling and pinching off a closure.
It is known, e.g., from U.S. Pat. No. 3,348,919, that finely divided aluminum, zinc, iron or copper metal react with liquid water at room temperature and atmospheric pressure in the presence of a catalytic amount of an alkali metal salt of a polyaminocarboxylic acid metal chelating agent. It is also known, e.g., from U.S. Pat. No. 1,798,862, that metal particles may be combined with a hygroscopic halogen salt of a metal in a desiccant composition, the function of the metallic particles being to provide heat of reaction to increase the hygroscopic qualities of the metal halide.
A need continues to exist for an efficient material which will scavenge moisture from a closed container but which does not have the disadvantages of requiring high temperature activation.